I just fitted one of these to my '08 also from Road Radio.
Really pleased. I got it in place of a 9280BT which was an absolute disaster. The 4021 has worked pretty much out of the box, hooks up to BT phone reliably, plays iPod and USB music great. I'm really pleased.
Only downside so far is I bought a 32GB USB stick, and it doesn't seem to like it - need to do some research, as it is fine with my16GB one.
Best to buy the proper steering wheel interface, as it saves some flapping around trying to locate wires and signals.
I have mine hooked up to a reverse camera too. Great stuff.
If you are even vaguely savvy about wires, then I wouldn't bother have RR fit it - most of it is plug and play. The only minor complication is the aerial booster, for which you just connect it up to the power aerial signal.
Cheers andy for the info . decided to buy one had it fitted and love it !! the only thing was know one could hear me on the phone so popped into road radio and the guy was really helpfull and sugested i try the kenwood software update which i downloaded onto a usb stick and now its fine . also brought the lead so i can watch the movies from my iphone .
also the guy at Redhill RoadRadio was really helpfull , A: